AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Characterization of an Humidified Tandem DMA System: Size and Humidity Dependent Efficiencies and Dispersion
XERXES LOPEZ-YGLESIAS, Ming Chee Yeung, Fred Brechtel, Chak K. Chan, Brechtel Manufacturing Inc.
Abstract Number: 431 Working Group: Instrumentation and Methods
Abstract Hygroscopicity is a critical property of atmospheric aerosol that describes particle response to changing ambient humidity. It governs the water content, optical properties and CCN activity of a particle by controlling the size at different relative humidity (RH) conditions. Comprehensive studies of hygroscopicity are necessary to elucidate aerosol impacts on global climate and regional visibility. The Tandem Differential Mobility Analyzer (TDMA) technique coupled with aerosol humidification has been widely used for studying aerosol hygroscopicity. In this study, we evaluate the performance of a commercial Humidified TDMA (BMI HTDMA, Model 3002) with respect to DMA sizing, particle transmission and dispersion as functions of size and relative humidity (RH), RH control, and growth factor (GF) measurements. The results of these experimental studies are compared to model predictions. Unique features of this particular HTDMA include a diffusion-based particle humidifier, a DMA design allowing selection of particles up to 2 µm diameter at only 5600 volts, and the ability to study the complete deliquescence and efflorescence cycle.